represents a point {x,y} in a planimetric cartographic grid using the projection proj.


represents a point {x,y,h} in a cartographic grid with height h with respect to the reference ellipsoid.


represents an array of cartographic grid positions.


represents a point in a cartographic grid obtained by projection from data in the given datum.


returns the cartographic grid position of the specified geographical entity.


  • Coordinates x, y in GeoGridPosition[{x,y},proj] must be given as numeric values, whose meaning is determined by the projection proj.
  • Height h in GeoGridPosition[{x,y,h},proj] can be given as a numeric object in meters or as a Quantity length.
  • Height h in GeoGridPosition[{x,y,h},proj] is geodetic height, measured with respect to the reference ellipsoid.
  • GeoGridPosition[{x,y,h,t},proj] includes a time t measured in seconds since the beginning of January 1, 1900 in the GMT time zone.
  • A GeoGridPosition object with no explicit height assumes height zero with respect to the reference ellipsoid. A GeoGridPosition object with no explicit time assumes the current date.
  • GeoGridPosition[pos,proj] converts from any geographic position to a grid point, essentially computing a cartographic projection. Any of the following coordinate types can be given: GeoPosition, GeoPositionXYZ, GeoPositionENU, GeoGridPosition.
  • GeoGridPosition[GeoPosition[{lat,lon}],proj] performs the direct projection from geodetic coordinates to the projected map.
  • Conversely, GeoPosition[GeoGridPosition[{x,y},proj]] performs the inverse projection from the map to geodetic coordinates.
  • Projections can be specified in the following forms:
  • "proj"named projection with default parameter values
    {"proj","param1"->val1,"param2"->val2,}projection with detailed parameters specified
  • Names of possible projections are given by GeoProjectionData[].
  • Default values of parameters for a particular named projection are given by GeoProjectionData[proj].
  • Values of height h and time t are preserved in projection computations.
  • GeoPosition[][prop] gives the specified property of a geo grid position.
  • Possible properties include:
  • "AbsoluteTime"date as number of seconds since Jan 1, 1900, 00:00 GMT
    "Count"number of positions in the GeoGridPosition object
    "Data"first argument of the GeoGridPosition object
    "DateList"date list {y,m,d,h,m,s} in GMT time
    "DateObject"full date object
    "Datum"datum of the GeoGridPosition object
    "Depth"point depth: 0 for a single position, 1 for a list of them,
    "Dimension"number of coordinates for each position
    "Elevation"numeric elevation in meters, with respect to the ellipsoid
    "GeoProjection"geo projection of the GeoGridPosition object
    "GridX"numeric x coordinate
    "GridY"numeric y coordinate
    "GridXY"numeric {x,y} pair
    "PackingType"Integer or Real if data is packed; None otherwise


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Basic Examples  (3)

Convert a geodetic position to a grid point using a spherical Bonne projection:

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Convert back to a geodetic position:

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Compute a spherical gnomonic projection using a custom setting for the central meridian:

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Compute a projection using explicitly specified projection parameters:

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Scope  (7)

Applications  (1)

Properties & Relations  (2)

Possible Issues  (1)

Introduced in 2008
Updated in 2019